1. Technical Field
The present invention relates to a screen and a projection system, and more particularly to a technology of a screen used in combination with a projector which projects light from a position close to the screen.
2. Related Art
A reflection type screen used in combination with a so-called front projection type projector needs to have high reflectivity to produce a bright image. This type of screen is further required to have high diffusibility sufficient for diffusing light to a desired area to obtain preferable visibility angle characteristics. A technology for obtaining high reflectivity and high diffusibility of the screen has been proposed in JP-A-58-52628, for example.
Recently, a projector capable of achieving close projection has been proposed. By the function of close projection, the projector can display an image on a large screen from a short projection distance. During the close projection, the projector applies light having a large incident angle to a screen. A screen in related art has a flat surface or a surface having small concaves and convexes to which paints in white, silver, or other colors are applied, for example. When light having a large incident angle is applied to this type of screen, most of the light reflected by the screen travels in a direction having a large angle with respect to the normal line of the incident surface. In this case, an image observed from the front of the screen does not have sufficient brightness. Moreover, the related-art screen which reflects not only light coming from the projector but also outside light as unnecessary light with high reflectance cannot obtain sufficient contrast in many cases. Particularly, under the environment containing a considerable amount of outside light, the light quantity of the supplied projection light needs to increase. According to the related-art technology, therefore, it is difficult to produce an image having high brightness and high contrast when the image is displayed on a large screen from a short projection distance.